The fictional bathroom can be a truly dangerous place. It is fraught with assassins, demons, and killer mutant creatures, to name a few. This is very possibly why Nobody Poops. A death or injury in the bathroom is a one-way ticket to a legacy of ignominy, and the prevalence of scary water-closet events seems to speak of a deeper human fear of vulnerability in this most private of places. Not to mention that some tricky assassins may exploit the assumed privacy and safety of the bathroom by Camping a Crapper.
In this sort of situation, the phrase "Make It Look Like An Accident" can take on disturbing subtext.
This generally has nothing to do with Ass Kicks You. See Swirlie for less injurious (hopefully) examples.
As a Death Trope, all Spoilers will be unmarked ahead. Beware.
In an episode of Gintama, the Yorozuya crew and the Shinsengumi are dealing with a supposed ghost (which turns out to just be an alien fly-woman, but they don't find that out until the end of the episode), and Kondo has an encounter with said "ghost" in the bathroom. When Hijikata slams his stall door open, Kondo is in there... head-first into the toilet bowl.
In Welcome Back, Frank the Russian beats the Punisher with a toilet.
In Nextwave The Captain uses the toilet cleaner and the toilet itself to deliver a smackdown to a parody of Dormammu
At one point in the The Darkness Jackie executes a hit on a heavily guarded mob boss by sending the Darkness through the plumbing. The mobster dies on the toilet and his guards are completly oblivious:
The Boondock Saints, wherein Connor McManus is handcuffed to a toilet as two Russian mobsters take his brother Murphy out to the alley to shoot him in the head. Connor, in a fit of Unstoppable Rage, tears the toilet right out of the floor, carries up to the apartment building roof and proceeds to send the toilet crashing down upon the head of the guy about to kill his brother as he jumps down himself onto the back of the second goon.
In the Andy Warhol film Lupe, it is suggested that Mexican actress Lupe Velez was found dead with her head in a toilet bowl. May or may not be Truth in Television.
The first victim of monstrous gigantic octopus that had taken over a cruise liner in Deep Rising is a woman who is hiding in a toilet. It is implied that she was forcefully sucked into the toilet, complete with blood-spatters.
Blown Away. Tommy Lee Jones uses the toilet bowel in his cell to create a shaped charge, which blows a hole through the prison wall.
Justified in Brannigan (1975). John Wayne is targeted by a hit-man who rigs up a Sawn Off Shotgun behind his hotel room door. In case he dodges the first Booby Trap, the hit-man plants a bomb in the toilet, knowing that a near-death experience would lead to a Bring My Brown Pants moment. Fortunately the Duke is smart enough to dodge both traps.
A prostitute has her head bashed against a toilet until it breaks (not her head, the toilet) in Dream Home.
The Alpha Bitch in Bad Reputation is beat against, then drowned in, a toilet. She had previously vomited in it.
In Casino Royale, James Bond's first kill (of two needed to earn 00 status) takes place in a bathroom. After much smashing of mirrors and porcelain, he drowns the guy in the toilet bowl. The mook was Playing Possum, however, and when Bond turns his back to retrieve his gun, the man leaps back up - and also cries out, giving Bond enough warning to spin around and shoot him. Cue opening credits.
GoldenEye has Bond knocking out his first mook this way. "Beg your pardon. Forgot to knock."
In the first Austin Powers film, an assassin tries to kill Austin while he's on the toilet. Austin turns the tables on him and kills him with a swirlie.
Two very long scenes in Copycat take place in a large public bathroom. Traumatic is the word.
One of the Discworld books describes death via red-hot pokers coming up through the privy hole. Kings live dangerous lives, sadly.
Dean Koontz's novel The Face describes the death of the protagonist's ex-friend, gangster Duncan "Dunny" Whistler. He owed some guys money, so they sent a couple of thugs around, who submerged his head in a toilet for long enough to put him into a coma and eventually kill him.
Ender of Ender's Game fights a bully in a shower room, using its unique properties to his advantage. Though he doesn't find out until much later, this had fatal side effects.
In Larry Niven and Jerry Pournelle's Footfall, a character is killed by holding his face in a toilet until he drowns.
In Michael Slade's Ripper, the toilet is one of many, many fixtures in the mansion which the serial killers Skull and Bones have turned into a Death Trap.
In Harry Potter Moaning Myrtle was killed in the bathroom and thus became the bathroom ghost.
In A Storm of Swords, Tywin Lannister is killed by his son Tyrion while in the lavatory. This is followed by a Brick Joke that "In the end, Tywin Lannister did not, in fact, shit gold."
Live Action TV
There was an episode of M*A*S*H where someone rigged a toilet to explode. It was an attempt by Cowboy to kill Henry Blake.
In Episode 2 of FlashForward we discover one of the Blackout victims was on the toilet and afterward had to resuscitate a coworker whose blackout had left him drowning in the urinal. Ewwww.Clean Pretty Reliable CPR disgustingly AVERTED!
George is killed by a space station's toilet seat in the series premiere of Dead Like Me. She's referred to in the Grim Reaper community as "Toilet Seat Girl," and try as she might, she can't escape the connection.
Supernatural does this at least once- one girl holds another's head in a toilet until she drowns.
Lupe Velez, the movie star in the '30s. Well, her career hit the skids, so she decided she'd make one final stab at immortality. She figured if she couldn't be remembered for her movies, she'd be remembered for the way she died. And all Lupe wanted was to be remembered. So, she plans this lavish suicide - flowers, candles, silk sheets, white satin gown, full hair and makeup, the works. She takes the overdose of pills, lays on the bed, and imagines how beautiful she's going to look on the front page of tomorrow's newspaper. Unfortunately, the pills don't sit well with the enchilada combo plate she sadly chose as her last meal. She stumbles to the bathroom, trips and goes head-first into the toilet, and that's how they found her. ...Will you ever forget that story?
CSI NY had an ep where a guy died after getting locked in a high tech prototype public toilet. Water filled it and drowned him.
Half-Life 2: Deathmatch. You have a gravity gun that can launch heavy objects at lethal velocity. Most of the maps have toilets that can be picked up with this gravity gun. Needless to say, this is an iconic combat technique, so much so that not only is the kill icon for thrown objects a flying toilet, it's also in the title screen for the game. There's also an achievement in the standard game for killing an enemy with a toilet. It's aptly named "Flushed".
Similar to the Fearsome Flush example below, Ghostbusters: The Video Game has a Cursed Artifact in the form of an absolutely disgraceful-looking toilet. When you collect it, your HUD reads: "This toilet is making frightening noises...is someone drowning?" Turns out the thing has a bloodthirsty demon bound to it, and was involved in an assassination many years ago.
Uncharted 3 features a Giant Mook as a Warmup Boss at the beginning of the game. After the fight goes into the men's bathroom, Drake defeats the guy by smashing a toilet cistern into his face.
Fallout 3. There are numerous traps in the game, but one the most sinister takes the form of a toilet rigged to explode whenever somebody uses it, which in your case is drink from it. Some toilets also have mines placed in the bowls or tanks.
Reversed in Kevin & Kell. Kevin resorts to a loan shark who shows up via his toilet. The next strip shows little Coney in potty training on the same toilet, and the results: One dead loan shark, one full bunny. When asked about the effects of the shark would be on the young girl, she shows in a later panel what results: she visits the bathroom with a fishing rod.
Grimtooth's Traps Too has the "Cranequin Goose" trap (a pressure-triggered crossbow hidden down the privy) and calls it "A fine way for a high and mighty hero to die."
The short-lived Cosmic Horror StoryCollectible Card GameHecatomb had at least one monster that was based around a killer toilet. Well, specifically, it was a carnivorous ooze-monster made from animated sewerage, which was depicted as having risen out of a toilet and eaten the unlucky cleaner.
The Real Ghostbusters toyline had Fearsome Flush, a "haunted" toilet that, when pushed forward, would sprout menacing eyes, teeth, and tongue.